Everything You Need to Know about Narcissists, Psychopaths, and Abuse - click on this link: http://www.narcissistic-abuse.com/faq1.html
Frustrating one's nearest and dearest has the dual "advantage" of simultaneously satisfying the narcissist's masochistic and sadistic urges. By withholding love, sex, intimacy, and the fulfillment of other people's desires and needs, the narcissist torments them even as he obstructs his own gratification. Self-sabotage, self-defeat, self-denial, and self-destruction (the martyred victim stance) serve to prevent the forming of attachment and intimacy and the potential for ultimate hurt and pain as they dissolve. But they also buttress the narcissist’s sense of superiority, uniqueness, and omnipotence. Only the strongest can overcome and vanquish desires, urges, needs, and emotions that easily overwhelm lesser mortals. The narcissist adheres to his idiosyncratic brand of ascetic religion in which he is both god and worshipper.
The narcissist’s inner monologue goes: “I reject everything that matters to other people, everything deemed valuable, worthwhile, meaningful, and desirable. I hold the weaklings who succumb to their emotions and drives in contempt: nothing they have or can possess or attain is of value to me. It is all meaningless.” The narcissist devalues the “commoners”, the average Joe, the pedestrian and routine, the “animalistic” (sex), and the socially conformist.
Thus, self-defeating, self-denying, and self-destructive behaviors and choices engender narcissistic supply because they uphold, demonstrate, and “prove” the superhuman nature of the narcissist, his utter titanic independence of society, of nature, and of others in interpersonal relationships. When narcissistic supply is in short supply, embarking on the path of self-negation is an efficacious shortcut to obtaining and securing. At the very least it draws astounded attention to the narcissist.
(From the book "Malignant Self-love: Narcissism Revisited" by Sam Vaknin - Click on this link to purchase the print book, or 16 e-books, or 3 DVDs with 16 hours of video lectures on narcissists, psychopaths, and abuse in relationships: http://www.narcissistic-abuse.com/thebook.html)